1. Field of the Invention
The present invention relates to a shift control device for a transmission mechanism of a motor vehicle, and more particularly to a column-type shift control device.
2. Related Art
A column-type shift control device is now used on a part of motor vehicles equipped with an automatic transmission (AT) or a continuously variable transmission (CVT). In this shift control device, a shift control lever provided in the vicinity of a steering wheel is swung about a lever mounting axis or pulled up to thereby set a desired shift range. When compared with a floor-type shift control device, the column-type shift control device can help expand the effective space within a passenger compartment of a motor vehicle and improve the occupying properties thereof, much attention being thus paid to the latter.
FIG. 14 is a drawing explaining a conventional column-type shift control device. In the figure, reference numerals 1 and 2 denote a steering wheel and a shift control lever for column shifting, respectively. The steering wheel 1 is mounted on a steering shaft not shown, and the shift control lever 2 is mounted on a shift shaft not shown. The conventional shift control device is mounted such that an axis S1 of the steering shaft is parallel with an axis of the shift shaft. Therefore, when the shift control lever 2 is swung (moved in a direction indicated by reference numeral d1), the shift shaft rotates through an angle corresponding to a distance that the shift control lever is shifted. On the contrary, when the shift control lever 2 is pulled up toward the driver (moved in a direction indicated by reference numeral d2), the shift shaft moves in the axial direction thereof a distance corresponding to a distance that the shift control lever is shifted. In other words, these mean that the shift control lever 2 has to be moved in the direction d2 in order to move the shift shaft in the axial direction without rotating the same shaft, while the shift control lever 2 has to be moved in the direction d1 in order to move the shift shaft axially without rotating the same shaft.
In the shift control device in which the shift shaft is disposed in parallel with the steering shaft as described above, when swing operating the shift control lever 2 to try to shift the transmissions, the driver tends to move the same lever in a direction indicated by reference numeral d1′ which deviates from the direction d1. In addition, when pulling up the shift control lever 2, the driver tends to move the same lever in a direction indicated by reference numeral d2′ which deviates the direction d2. The reason for these deviations from the intended operating directions is because the driver tends to operate the shift control lever 2 with reference to a rotational center P of his or her shoulder. When thinking of swing operations by the driver, the driver tends to rotate the shift control lever 2 at a distance equal to a distance from the rotational center P of his or her shoulder to the shift control lever 2. In other words, the driver tends to swing the shift control lever while pulling it up by a distance equal to a deviation between the direction d1′ and the intended direction d1. If a distance the shift control lever 2 is pulled up due to the aforesaid lever operation exceeds a predetermined pull-up distance which regulates lever shifting between two gear positions, an unintended gear position (for instance, a parking gear position) is engaged irrespective of a driver's intention to engage a currently intended gear position (for instance, a drive range position).
Next, a pull-up operation of the shift control lever 2 will be considered with reference to a case where the gears are shifted from the parking position to any of the other gear positions. This gear shifting needs a lever operation in which the shift control lever 2 which is being located at the parking position is pulled up a predetermined distance in the direction d2 before it is swung. In this pull-up operation, the shift control lever 2 can be shifted in the direction d2, but the lever is restricted from being shifted in the direction d1 by the mechanism of this shift control device. Since the driver tends to pull up the shift control lever in a direction toward the rotational center P of his or her shoulder (move the shift control lever in the direction d2′), the shift control lever 2 tends to be shifted toward the direction d2′. In other words, the driver tends to pull up the shift control lever 2 while applying thereto a force in a direction deviating from the intended direction d2 toward the direction d1′. However, since the movement in the direction d1′ is restricted, the shift control lever 2 is shifted in the direction d2 which is different from the driver's intended direction d2′. As a result of this, there may be a risk of the driver eventually feeling an unnatural shift lever operation feeling.